The present invention relates to a method and apparatus for opening a resin-sealed body.
Conventionally, when an integrated circuit chip, which uses polyimide to form its protective film and interlevel film and is sealed with a resin, is to be opened, a recess is formed by machining on the surface of the sealing resin above the integrated circuit chip in advance by using a drilling means such as a grinder, and after that fuming nitric acid is dropped into the recess formed by machining, or the whole integrated circuit is dipped in fuming nitric acid filled in a container, thereby dissolving and removing the sealing resin.
As another opening method, a method of mechanically removing the sealing resin on the integrated circuit chip completely with a polisher is known.
With the dissolving and removing method described above, particularly in the case of a resin-sealed integrated circuit using polyimide to form its protective film and interlevel film, the polyimide layers are undesirably dissolved by fuming nitric acid. Accordingly, aluminum interconnections sandwiched by the polyimide layers sometimes move as the polyimide layers are dissolved.
If the method of mechanically removing the sealing resin on the integrated circuit chip by using the polisher is employed, when a sample is to be fixed with respect to the polisher, sometimes the sample is not precisely horizontal with respect to the moving direction of the wheel of the polisher, or excessive grinding is difficult to avoid. For this reason, part of an upper aluminum interconnection which is originally intended to be left is undesirably drilled and removed.
According to a so-called heating and mechanical breaking method, which is generally employed in opening a polyimide-free integrated circuit, of removing the sealing resin of the integrated circuit by temporarily heating the integrated circuit and after that applying a mechanical stress to it, the polyimide layers are undesirably deformed by heating, and the upper aluminum interconnection originally intended to be left is accordingly deformed, thereby causing partial disconnection.
As mentioned above, with any of the methods described above, the upper aluminum interconnection undesirably moves, or part of the aluminum interconnection is undesirably drilled and removed. Hence, when failure analysis and the like of the integrated circuit are to be performed, the aluminum interconnection structure cannot be grasped, or the disconnected aluminum interconnection cannot be observed.
The present invention has been made in view of the above problems, and has as its object to provide a method and apparatus for opening a resin-sealed body, with which when failure analysis and the like of a predetermined circuit including an integrated circuit are to be performed, movement of an upper aluminum interconnection is prevented and excessive drilling and removal are prevented, so that an aluminum interconnection structure can be grasped and a disconnected aluminum interconnection can be observed.
In order to solve the above problems and to achieve the above object, according to the present invention, there is provided an apparatus for opening a resin-sealed body obtained by sealing a predetermined circuit, including an integrated circuit covered with a layer/film member, with a sealing resin, characterized by comprising drilling apparatus for drilling the sealing resin on the layer/film member by a depth corresponding to a predetermined thickness, observing apparatus for observing a drilling state in enlargement, laser irradiation apparatus for partially drilling the drilled sealing resin by laser irradiation up to the layer/film member, and container apparatus for storing a liquid that does not dissolve the layer/film member, the resin-sealed body being dipped in the liquid and ultrasonic vibration being applied to the container apparatus so that the sealing resin is removed from the layer/film member.
The present invention is also characterized in that the depth corresponding to the predetermined thickness is a depth equal to a diameter of a gold ball of a gold wire that connects the predetermined circuit to a lead.
The present invention is also characterized in that the laser irradiation apparatus has a moving mechanism for performing partial drilling while shifting a position thereof, and a YAG laser generator.
The present invention is also characterized in that the layer/film member is made of polyimide, and the YAG laser generator has an output energy of not more than 90 mJ.
The present invention is also characterized in that the liquid does not chemically dissolve the layer/film member.
According to the present invention, there is also provided a method of opening a resin-sealed body obtained by sealing a predetermined circuit, including an integrated circuit covered with a layer/film member, with a sealing resin, characterized by comprising the steps of drilling the sealing resin on the layer/film member with drilling means by a depth corresponding to a predetermined thickness, observing a drilling state in enlargement with observing apparatus, partially drilling the drilled sealing resin with laser irradiation apparatus by laser irradiation up to the layer/film member, and removing the sealing resin from the layer/film member with container apparatus which stores a liquid that does not dissolve the layer/film member, the resin-sealed body being dipped in the liquid and ultrasonic vibration being applied to the container apparatus.
The present invention is also characterized in that the drilling step comprises performing drilling by a depth corresponding to the predetermined thickness and equal to a diameter of a gold ball of a gold wire that connects the predetermined circuit to a lead.
The present invention is also characterized in that the step using the laser irradiation apparatus comprises performing partial drilling while shifting an irradiation position with a YAG laser generator having a moving mechanism.
The present invention is also characterized in that partial drilling is performed with one stroke.
The present invention is also characterized in that the layer/film member is made of polyimide, and in the step using the laser irradiation apparatus, the YAG laser generator has an output energy of not more than 90 mJ.
The present invention is also characterized in that in the step using the container apparatus, the liquid does not chemically dissolve the layer/film member.